• Daniel Vetter's avatar
    drm/i915: use pipe_config for lvds dithering · d8b32247
    Daniel Vetter authored
    Up to now we've relied on the bios to get this right for us. Let's try
    out whether our code has improved a bit, since we should dither
    always when the output bpp doesn't match the plane bpp.
    - gen5+ should be fine, since we only use the bios hint as an upgrade.
    - gen4 changes, since here dithering is still controlled in the lvds
      register.
    - gen2/3 has implicit dithering depeding upon whether you use 2 or 3
      lvds pairs (which makes sense, since it only supports 8bpc pipe
      outpu configurations).
    - hsw doesn't support lvds.
    
    v2: Remove redudant dither setting.
    
    v3: Completly drop reliance on dev_priv->lvds_dither.
    
    v4: Enable dithering on gen2/3 only when we have a 18bpp panel, since
    up-dithering to a 24bpp panel is not supported by the hw. Spotted by
    Ville.
    
    v5: Also only enable lvds port dithering on gen4 for 18bpp modes. In
    practice this only excludes dithering a 10bpc plane down for a 24bpp
    lvds panel. Not something we truly care about. Again noticed by Ville.
    
    v6: Actually git add.
    
    Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
    Reviewed-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
    Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
    d8b32247
intel_display.c 260 KB